Driver

ABSTRACT

A driver for use in orthopedic surgery having a generally elongate housing adapted for single-handed gripping operation. The driver includes an engagement mechanism associated with the housing for releasably engaging the proximal end of a longitudinally extending driven member and includes a driven member, such as a flexible drive spindle, for rotatably driving the engagement mechanism. The driver further includes shield that is supportingly connected with an end of the housing so as to extend co-axially with and fully circumscribe the driven member. The distal end of the shield terminates in an end portion adapted to be placed against a surface of a body part into which the member is driven. The driver also includes a mechanism to permit relative movement in an axial direction between the engagement mechanism and the end portion for advancement into and retraction from the surface so that, in use, single-handedly, the driven member is always fully shielded and supported. In the preferred form of the invention the relative movement between the engagement mechanism and end portion is achieved by a longitudinally retracting shield. In other embodiments the shield is fixed and the engagement mechanism is advanced internally within the housing.

FIELD OF THE INVENTION

The present invention relates to a single handed power driver withintegral shield mechanism for drilling and inserting fasteners such asscrews and the like.

The invention has been developed primarily for use in orthopaedicsurgery and will be described hereinafter with reference to thisapplication. However, it will be appreciated that the invention is notnecessarily limited to this particular field of use.

BACKGROUND OF THE INVENTION

Orthopaedic surgery often involves the joining of two or more segmentsof a bone. This join is usually accomplished by bolting, screwing orwiring the segments directly together, or bolting, screwing or wiringthe segments to a common plate or other intermediate joining member. Itis normally necessary to use some form of powered driver to drive adrill bit, screws, Kirschner wire or other device or implement into thebone to facilitate the join.

The positioning of the bolts, screws or wires in the bone is extremelycritical for the integrity of the joint and the subsequent healingprocess. Accordingly, in addition to the usual complications and stressgenerally associated with overall patient well being in surgery, theorthopaedic surgeon also has to ensure the driver is very accuratelypositioned. This is difficult as it often requires holding the bonesegments to be fixed in an exact orientation whilst simultaneouslyaiming, supporting and operating the driver.

To assist in overcoming these problems, a separately supportable drillguide plate or similar is initially positioned adjacent the bone orprosthesis being drilled in order to ensure that the drill bit orsimilar passes into the bone at the desired location and on the desiredcourse. Ideally, the guide plate also serves to minimise damage to thesoft tissue surrounding the bone which may get caught by the rotatingdrill bit, screw or wire.

It will be appreciated that the above procedure requires the surgeon tohold in position the fragments to be fixed whilst simultaneously usingthe power drill and positioning and holding the drill guide. Clearly,this is something that is difficult, if not impossible to achieve withany accuracy with only two hands, so often the surgeon has to depend onthe help of an assistant. However, this is not only labour intensive butis rarely satisfactory, as the assistant is not generally in a positionto maintain or judge correct alignment and their presence may evenrestrict access to and/or sight of the surgical opening.

To further complicate matters, the prior art procedures often requireuse of a separate tool to increase and/or determine the depth of travelof the drill or other driven member.

It is an object of the invention to overcome or at least ameliorate oneor more of these deficiencies of the prior art or at least offer auseful alternative thereto.

DISCLOSURE OF THE INVENTION

According to a first aspect of the invention there is provided a compactsingle unit driver with integral shield device for use on a body or bodypart in orthopaedic surgery or the like, the driver including:

a housing adapted for single handed gripping operation;

engagement means associated with said housing for releasably engagingthe proximal end of a longitudinally extending driven member;

drive means for rotatably driving the engagement means;

longitudinally extending generally supporting non rotating shield meansconnected with an end of the housing so as to extend co-axially with andcircumscribe said driven member, the distal end of said shield meansterminating in an end portion adapted to be placed against a surface ofthe body part into which or toward which the member is to be driven; and

means to permit relative movement in an axial direction between saidengagement means associated with said housing and said end portion foradvancement into or toward said surface or body part and retractiontherefrom so that, in use, single handedly, the rotating engagementmeans and portion of said driven member above said surface of said bodypart are always fully shrouded by means of the housing and/or the shieldmeans.

By reference herein to an integral shield device it is meant simply thatthe shield device forms a permanent part of the driver as a whole. Assuch the shield need not necessarily be integrally formed with thehousing, but may be separately manufactured and captively retained in asuitable manner.

Desirably, the shield means is sized to also act as a guide for thedriven member. However, in some embodiments the shield means may includeseparately identifiable guide means at or adjacent the end portion ofthe shield.

The driven member may be a drill bit, screw, Kirschner wire or othersurgical implement, tool or device. Preferably, the device is configuredsuch that the distal point of the driven member in the inoperative modeprotrudes slightly from the shield means to facilitate accuratepositioning prior to driving and is, ideally, retractable, relative tothe end portion, prior to operation.

The driven member may directly engage the engagement means such as inthe case of a drill bit. Alternatively the driven member may engage anintermediate member that directly attaches to the engagement means suchas in the case of an intermediate bit to engage a screw.

In a first preferred form of the first aspect, the engagement means aregenerally fixed relative to the housing and the shield means areretractable into said housing as the driven member is advanced into thesurface. Preferably, the shield means is retractable against a biasingmeans such that as the driven member is advanced or retraced by movementof the housing, the shield means is urged into maintained contactagainst the surface into which the member has been driven. In anotherform, the shield means comprises two or more cylindrical concentrictelescoping portions that decrease in diameter towards the end portion.

Desirably, in this first preferred form the shield means comprises agenerally cylindrical member, which, preferably, is marked externallywith gradations indicative of the penetration depth of the driven memberbeyond the shield end portion. In another preferred form the depthindication is provided via a direct window on the housing or via adisplay coupled to an electronic displacement transducer.

This first embodiment provides an elegantly simple solution to the priorart problems, enabling the driver to be advanced by applying a linearlyacting driving force to the housing which drives in the member andsimultaneously overcomes the biasing force on the shield. In this mannerthe drill can be accurately positioned and guided and the softsurrounding tissues protected from damage by the shield, the retractionof which also directly or indirectly provides an indication of depth ofpenetration. All this is achieved with a compact unit that requires onlyone handed operation.

According to a second embodiment of the first aspect of the invention,the shield means is rigidly connected to or forms part of the housingand the engagement means are adapted to move internally relative to thehousing between a retracted position in which the driven member issubstantially located within the shield means and an extended positionin which a part of the driven member protrudes from the shield means asit is driven into the surface.

In this second embodiment a plurality of changeable shield portions maybe provided for use with the driver. The bore of the guide means in eachof the shield means may be produced in one of a range of diameters toreceive different diameter driven members. A supporting clearance fit isgenerally provided between the bore of the guide and the driven member.However, in some cases where the driven members have sufficientrigidity, one shield of, for example, 4.5 mm internal diameter issuitable for use with all drills and wires under, say, 4.0 mm.

In both embodiments, the drive means preferably includes a first motorwhich is desirably electrically or pneumatically powered. The firstmotor may be internal or external the driver. Preferably, in the firstembodiment the motor is external.

In one variation of the second embodiment the driver includes atelescopic coupling operatively connecting an internal first motor tothe engagement means. In this embodiment the motor is fixed relative tothe shield means and the engagement means travels along the rotationalaxis of the driven member to move the driven ember between the retractedand extended positions. In another variation of the second embodimentthe internal first motor and the engagement means travel along therotational axis together.

Alternatively, in either embodiment, the first motor may be external thedrill with a flexible coupling, such as a cable drive, operativelyconnecting the first motor to the engagement means.

The first motor may, in the second embodiment, be adapted to bothrotationally drive the engagement means and extend and retract theengagement means and hence the driven member.

In an alternative arrangement of the second embodiment the first motordrives the engagement means only and a second motor is adapted to extendand retract the drill bit.

The drill of the second embodiment may include gear means operativelyconnected to the any or all of the motor or motors or engagement meansfor extension and retraction of the engagement means. The gear means mayinclude selectively operable advancement and retraction gears forextending and retracting the engagement means. In other embodiments asingle gear is used with a bidirectional motor.

In further variations of the second embodiment the engagement means maybe advanced and retracted manually.

Optionally, means can also be provided to give an external indication asto travel of the engagement means which in this second embodiment isindicative of depth of penetration of the driven member.

The driver may also include a variable speed gearbox between the firstmotor and the engagement means. Alternatively the first motor may be avariable speed motor. If desired, the first motor also provides a fixedslow speed. In all embodiments the engagement means is preferably afemale/male connector adapted to engage a corresponding male/femaleconnector provided on the driven member. The engagement means can alsoinclude other types of connectors such as snap-lock fittings or chucks.

In one form the female connector and the proximal end of the drivenmember preferably include a recess and a correspondingly shaped spigotrespectively. In other embodiments the recess and spigot have square,triangle, hexagonal or star shaped cross sections. The recess and spigotmay, alternatively, include mating threads.

The driver may also include a plurality of different sized engagementmeans to cater for different sized driven members. In an embodiment thedriver includes a magazine adapted to hold a plurality of driven membershaving commonly sized drive head portions, the magazine being adapted topermit rapid engagement of the individual driven members with theengagement means. Desirably, the magazine holds a plurality of likedriven members of different size or a selection of differentcomplementary driven members.

In one version of the second embodiment, the driver housing, which isattached to or includes the shield and optional guide portion, isadapted to encase the engagement means. The housing preferably includesexternal manual controls for the driven member rotation, advancement andretraction of the driven member. The manual controls are preferablypositioned on the housing for left or right hand manipulation. Thedriver may alternatively or additionally include remote controls.

The driver may be configured such that the driven member extends andremains in contact with the surface a short distance from the endportion so as to permit the driven member to engage the surface andthereafter drive itself into the surface. This configuration isapplicable when the driven member is, for example, a self tapping screwwhich, when rotated, will continue to advance itself after initialengagement is made with the surface.

The driver may also be configured to continually advance the drivenmember into the surface. This configuration is applicable when thedriven member is, for example, a drill bit which needs to be bothrotated and advanced to drive it into the bone or similar surface.

Desirably, the end portion of the shield includes means, such asserrations or spikes, to help prevent the tip of the driver from"wandering" once in contact with the relevant surface.

In one preferred form the driver is provided with a plurality of drivenmembers of various type and size each having at their proximal ends acommon sized and shaped head portion for engagement with correspondinglysized drive coupling forming the engagement means on the driver.

In another preferred form the driver is provided with one or moreadaptors for driven members, each adaptor comprising at one end astandard sized and shaped head portion for engagement with acorrespondingly sized drive coupling forming the engagement means on thedriver, said adaptor being configured at said other end remote saidfirst end for torque transmitting attachment to a driven member of agiven size.

Preferably, the adaptor is made of a plastics material or the like, thetorque transmitting attachment to said driven member being achieved, forexample with drill bits, by moulding onto an end of said driven memberthat either incorporates a driving flat or has been flattened orroughened to reduce the likelihood of rotation within the adaptor. Inthe case of screws or the like, the torque transmitting attachment isvia a suitable shaped drive portion selected to correspond with thedrive recess provided in the head of the screw.

Desirably, the head portion of the second and third aspects is astandard shape such as round, hexagonal, square, d-shaped or the like.With the round head portion a standard chuck may comprise the drivecoupling. In the other variations where the head portion may have asquare or hexagonal cross section, it is preferable the drive couplingis correspondingly sized and shaped.

Preferably, the driver according to the first aspect of the inventionincludes an engagement means sized and configured to receive drivenmembers according to the second aspect of the invention or drivenmembers incorporating adaptors according to the third aspect of theinvention.

Desirably, the driver is of a general pencil-style shape. However, otherconfigurations, including a pistol-style arrangement, are possible.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will now be described, by way ofexample only, with reference to the accompanying drawings in which:

FIG. 1 is a first embodiment of a fixed shield driver according to thefirst aspect of the invention with the driven member in the extendedposition;

FIG. 2 is a partial view of the driver shown in FIG. 1 with the drivenmember in the retracted position;

FIG. 3 is a sectional side view of a second embodiment of a fixed shielddriver according to the first aspect of the invention;

FIG. 4 is an enlarged view of a telescopic coupling used in the driverof FIG. 3 in extended and retracted positions;

FIG. 5 is a partial sectional side view of a third embodiment of a fixedshield driver according to the first aspect of the invention;

FIG. 6 is an exploded perspective view of a fourth embodiment fixedshield driver according to a first aspect of the invention;

FIG. 7 is an internal perspective view of a fifth embodiment fixedshield driver according to a first aspect of the invention;

FIG. 8 is a telescopic coupling for use with the driver shown in FIG. 7;

FIG. 9 is a diagrammatic end view of a gear assembly for use with thedriver shown in FIG. 7 with the advancing gears engaged; and

FIG. 10 is a diagrammatic cross-sectional end view of the gears shown inFIG. 9 with the retraction gears engaged;

FIG. 11 is a diagrammatic perspective view of a first embodimentretracting shield driver according to the first aspect of the invention;

FIG. 12 is a schematic sectional view of the driver shown in FIG. 11;

FIG. 13 is a side view of the driver shown in FIG. 11;

FIG. 14 is a top plan view of the driver shown in FIG. 13;

FIG. 15 is an inverted plan view of the driver shown in FIG. 13;

FIG. 16 is a front end view of the driver shown in FIG. 13;

FIG. 17 is a rear end view of the driver shown in FIG. 13;

FIG. 18 is a part view of the driver shown in FIG. 11 illustrating theshield in the retracted position during use;

FIGS. 19a-c are schematic representations of how the retractable shielddriver operates with a screw and intermediate drive adaptor;

FIGS. 20a-c illustrate examples of quick release drive coupling suitablefor use with drivers of the first aspect of the invention and drivenmembers in accordance with the second and third aspects of theinvention;

FIG. 21 is a schematic part view of an alternate telescoping shieldarrangement for use with the retractable shield driver according to thefirst aspect in the invention;

FIG. 22 is a schematic representation of a full driver and driven memberkit in accordance with the invention; and

FIG. 23 is a schematic view of a surgical opening made in preparationfor a bone chilling operation using the drivers hereinbefore described.

PREFERRED EMBODIMENTS OF THE INVENTION

Preferred embodiments of fixed shield drivers according to the inventionwill now be described with reference to FIGS. 1 to 10 of theaccompanying drawings.

Referring firstly to FIGS. 1 and 2, there is shown a preferredpencil-style driver 10 for use in orthopaedic surgery or the like. Thedriver includes a shield 12 having a bore 14 surrounded by an adjacentguide portion 15 of the shield 12 sized and adapted to receive a drivenmember in the form of drill bit 16. The guide portion terminates in adistal end portion 18 which is adapted to be placed against the surfaceinto which the drill is to be driven. The driver 10 also has anengagement means in the form of female connector 20 for releasablyengaging the driven end 22 of the driven member 16.

A drive means, in the form of electric motor 24, is used to rotate theengagement means 20 and drill bit 16. The connector 20 is coupled to themotor 24 by a drive shaft 26. The drive shaft 26 is rotated by the motor24, and is also able to slidably pass through motor 24 in the directionof longitudinal axis 25. The end 27 of the drive shaft opposite theconnector is connected to second motor 28.

The driver has a generally cylindrical body 30 of which shield 12 formsan integral part. The distal end 31 of the body 30 contains an internalgear form 32 adapted to engage the external gears 33 of the second motor28.

The bore 18 of the guide portion 15 of the shield 12 is sized as aclearance fit around the outer diameter of the drill bit 16. A number ofinterchangeable shields 12 having correspondingly sized bores areprovided to accommodate various sizes of drill bits, screws, wire or thelike. However, depending on the stiffness of the driver members, oneshield/guide size may be adequate for a range of driven members.

The female connector 20 includes a recess 35 and the proximal end 22 ofthe drill bit has a correspondingly shaped spigot 36. In this embodimentthe recess and spigot have a square cross-section. It will beappreciated that various other cross-sections may be used and they mayinclude snap-lock fittings or similar to provide a secure releasableconnection between the connector and the drill bit.

The body 30 also includes external manual controls (not shown) to allowthe surgeon to control the speed of the drill bit rotation, advancementand retraction. Remote controls, such as foot pedals (not shown) arealso available for use with the driver 10. Electrical power for thedriver is supplied through a cable 34.

In use, the spigot 36 of the drill bit is inserted into the recess 35 ofthe connector 20. The second motor 28 is then used to position theengagement means such that the distal end 18 of the drill bit is withinthe guide portion 15. This is achieved by energising the second motor 28and thereby rotating the gears 33 causing the second motor to travel inthe direction of the axis 25. As the drive shaft length is fixed, thetranslational travel of the second motor 26 results in identicaltranslational travel of the female connector 20 and the drill bit 16.The end 18 of the guide portion is then placed adjacent the bone orother apparatus into which the surgeon intends to drive the drill bit.The surgeon then uses the first motor 24 to rotate the drill bit and thesecond motor 26 to advance it from within the guide and extend the drillbit into the bone or other surface.

The driver according to the invention obviates the need for the surgeonto manipulate and position a separate guide plate and therefore providesa simplified surgical procedure with more accurate positioning of thedrill bit or the like. In particular, the driver allows accuratepositioning of the drill bit whilst still providing a shield and/orguide so as to overcome the difficulties associated with driving throughsoft tissue and the like.

If a screw is driven instead of a drill bit, then an intermediate member(not shown) may be needed which has one end adapted to connect to theconnector 20 and another adapted to releasably engage the screw head.

FIGS. 3 and 4 show a second embodiment of a fixed shield driveraccording to the invention in which like numerals will be used todesignate corresponding features.

In this embodiment, a telescopic coupling 40, comprised of squarecross-section inner and outer portions 40 and 42 respectively, isconnected to the drive shaft 28 intermediate the motor 24 and theconnector 20. Internal gears 46 are provided in the body 30 forward ofthe motor and are engaged by a worm gear 48 attached to the drive shaft.In this way, rotation of the drive shaft by the motor 24 causes thedrill bit 16 to rotate about the axis 25 and also translate along theaxis 25 as the worm gear 48 is driven along the gears 46. The movementof the connector 20 relative to the motor 24 is accommodated by thetelescopic coupling 40, as exemplified in the two extreme positionsshown in FIG. 4. The pitch of the gears 46 permits optimisation of therelationship between the rotational speed of the drill bit and itstranslational advancement and retraction into the bone or other surface.

Turning now to FIG. 5 there is shown a third embodiment of a fixedshield driver according to the invention in which like numerals willagain be used to designate corresponding features.

In this embodiment, the distance between the first motor 24 and theconnector 20 is fixed by coupling 50. The body 30 includes an internalrack gear 52 engaged by a worm gear 54 coupled to second motor 26. Thesecond motor is mounted to the rear of the first motor 24.

Rotation of the worm gear 54 causes it to travel along rack 52,simultaneously translating the first and second motors, the connector 20and the drill bit 16.

The third embodiment of the fixed shield driver according to the firstaspect of the invention also includes a replaceable stepped guideportion 58 which is a press or snap lock fit into the distal end 60 ofdriver body 30.

A fourth embodiment of fixed shield driver is shown in FIG. 6. Thisembodiment also includes a second motor 26 coupled to the rear of firstmotor 24 and uses a worm gear 62 to advance and retract the motor alonggears 64. The external circumference of the drive motor 24 is providedwith ridges 66 which are configured to slide along correspondinglyshaped recesses 68 provided in the two halves of the drill body 70 and72. This embodiment also includes a stepped guide 74 with a replaceablebore section 76. The replaceable bore section 76 allow the internaldiameter of the guide bore to be altered whilst leaving the guide itselfin place. The drill bit 78 includes an annular recess 80 adapted to snaplock into the connector 20.

Turning now to FIGS. 7 and 8 there is shown the internal components of afifth embodiment fixed shield driver encased by the driver body 30 shownin phantom. In this embodiment, the first motor 24 is directly attachedto the end of the connector 20. The other end of the motor is fixed inrelation to a gear mechanism 82 connected to a second motor 84 by atelescopic coupling 86. The gear mechanism 82 includes an opposed pairof advancement gear racks 88 and an opposed pair of retraction gearracks 90.

The second motor 84 rotates the worm gear 92 which can be selectivelyengaged by one of the opposed pairs of gear racks 88 or 90. The racksare surrounded by a spring steel casing 94, best shown in FIGS. 9 and10, which deforms under digital pressure to bring one of the gear setsinto engagement with worm gear 92.

As shown in FIG. 10 when digital pressure is applied to the retractinggear set 90 they are brought into engagement with worm gear 92 androtation the worm gear causes the first motor, the connector and a tap96 to retract into the shield 12.

Similarly, if the advancement gear tracks are pressed into engagementwith worm gear 92 then the same directional rotation of the motor willcause the first motor 24, the connector 20 and the tap 96 to advance andprotrude from the end of the guide.

In a variation of this embodiment only a single opposed pair of gearracks are used and a switch is provided to reverse the direction of thesecond motor 26 in order to selectively advance or retract the connector20 and associated equipment.

In further embodiment of the driver (not shown) the motor is fixedrelative to the connector and is able to be manually translated withinthe drive body. This embodiment has particular application in thedriving of self-tapping screws and the like which advance themselvesinto the bone after initial engagement is made as the connector andaccompanying motor are drawn forward by the screw due to theself-tapping action.

A preferred embodiment of the retractable shield driver according to thefirst aspect of the invention will now be described with reference toFIGS. 11 to 22 of the accompanying drawings.

The primary difference between this embodiment and those previouslyillustrated and discussed above, is that no separate mechanism isprovided for advancing the engagement means relative to the housing.Instead, the advancement is achieved by applying a linearly acting loadto the driver, the shield being configured to retract into the housingas the driven member advances, thereby ensuring that the surroundingsoft tissue is protected at all times.

This is a very simple solution that provides excellent feel for theoperator as well as providing a direct visual indication of thepenetration of the driven member, either directly by means of theretracting shield, or, via a window or electronic indicator on thehousing itself These features are described in more detail below.

Turning first to FIGS. 11 and 16, it can be seen that the driver 100once again has a generally elongate housing 102 that is contoured andotherwise adapted for single handed gripping operation. Engagementmeans, shown generally at 104, are provided within the housing forreleasably engaging the proximal end of a longitudinally extendingdriven member such as the drill bit 106 shown. Drive means are againprovided for rotatably driving the engagement means which, in theembodiments shown comprises a flexible drive shaft 108 which isexternally driven by an electrical pneumatic motor 128 (see FIG. 22).

The driver 100 also includes a generally cylindrical retractable shield110 which is biased outwardly from the housing by means of a captivecompression spring 112. The end portion 114 of the shield 110 ispreferably serrated or includes spikes thereon to grip the bone surfaceto be drilled in order to prevent the drill from wandering during use.

In the embodiments illustrated, the generally cylindrical shield 110 ismarked with gradations 116, such that as the shield retractstelescopically within the housing 102 the operator is provided with avisual indication as to the effective penetration depth of the drill106. In other embodiments the depth indication is achieved via a windowprovided in the housing which shows a marker on the shield 116retracting into the housing against an appropriate scale. Other moresophisticated versions may include some form of electrical or electronicdisplay responsive to an appropriate displacement transducer.

One preferred shape of the driver housing 102 is shown most clearly inthe orthogonal views depicted in FIGS. 13 to 17. In this particulararrangement the button 118 is conveniently located on the upper portionof the housing at or adjacent the location at which the operator's indexfinger would rest during use. In other embodiments, not shown, theon/off mechanism is remote from the driver housing 102 and may be, forexample, foot operated.

Turning next to FIGS. 20a-c there is shown a range of quick releasecoupling arrangements suitable for use with various embodiments of thedrivers previously illustrated. The left most design illustrates aspring-ball type connector, the centre design shows a tapered hexagonalsectioned male drive and corresponding hexagon female socket; and theright most design shows a standard tapered chuck type coupling.

It will be appreciated that with the previously described retractableshield drivers, either long drill bits or other driven members will berequired because of the retraction of the rigid shield 110 into thehousing body, particularly if a conventional chuck device is used as theengagement means, or an engagement means must be used which has anoverall diameter that is less than the internal diameter of the shield.In the latter case, preferred narrow style engagement means includepreferably slightly tapered male driver connectors having appropriatedrive flats that are adapted to frictionally engage correspondinglyshaped female recesses in the proximal end portions of the drivenmembers.

These problems are ameliorated in one alternate embodiment by use of acollapsible shield configuration as shown in FIG. 21 which comprises aplurality of telescoping cylindrical portions 111 which progressivelynest one within the other as the driver advances against the surface.Accordingly, when the shield is in the fully retracted position, itextends into the housing only a fraction of it's overall extendedlength, thereby enabling shorter drill bits and the like to be usedwithout placing undue constraints on the overall diameter of the chuckdevice/engagement means.

Turning next to FIG. 22, there is shown a preferred full driver anddriven member kit in accordance with the invention. The kit illustratedincludes the retractable shield driver 100 mounted on a support rack 120adjacent a set of various drilling members 122. The rack includes afixed upper surface 124 and a selectively releasable gripping mechanismshown generally at 126. Separately mounted at some convenient locationis a main drive motor 128 from which extends the flexible drive cabling130 which attaches to the rear end of the driver 100.

In use, for example, the wound adjacent a bone to be drilled would beopened as shown in FIG. 23. The driver, having been pre-loaded with theappropriate drilling member, would then be taken in one hand and the endof the drill protruding from the end portion 114 would be accuratelypositioned on the bone 132. The tip of the drill member is thenretracted relative to the end portion 114 of the shield 110 by eitherletting out the shield against the biasing spring from a partiallyretracted starting position until it hits the surface or alternativelyby applying pressure to the driver so that the engagement means 104retracts a short predetermined distance by a suitable mechanism so thatagain the end portion 114 comes into contact with the bone.

The driver can then be actuated directly or indirectly and the drill 106advanced into the bone by applying a linear force to the housing 102.Once the drill has reached the predetermined depth as indicated on theshield or other depth indication device, the driver housing can beretracted, the biasing spring 112 keeping the shield closely adjacentbone at all times thereby preventing the soft tissue from gettingentangled in the rotating drill bit (see for example FIG. 18).

In the event that the operation requires a further separate drillingoperation or the like be performed, the driver is simply returned to therack 120 in alignment with a vacant driven member location as shown.Preferably the rack has been configured such that the shield 110 willnot be able to pass through the apertures formed in the upper surface124. This enables the driver to be pushed down in a manner whereby theshield 110 is retracted into the housing 102 and the driven member isexposed. When the distal end of the driven member has been loweredsufficiently, the gripping means 126 (which may comprise any suitabledevice) is actuated such that the drill bit is firmly held. The driver100 is then retracted, thereby pulling the drill bit from the quickrelease coupling. The driver is then advanced to the station that holdsthe next desired drill member, the drive end of the driven member simplyclicking into connection with the engagement means of the driver. Firstmaking sure that the gripping mechanism 126 has not been actuated, thedriver and newly assembled driven member can then be released from therack ready for operation. This procedure can be repeated as necessary,making the entire process fast, clean and accurate with no additionalassistance being required.

When it is desired to use the driver to insert a screw or the like, anintermediate adaptor 134 is used such as is shown in FIGS. 19a-c. Theadaptor has one end adapted for releasable connection to the engagementmeans and the other adapted for driving the screw.

In the preferred forms of the retractable shield driver according to theinvention, a high torque reasonably low fixed speed drive is provided.However, it will be appreciated that other variations are possible withdifferent fixed speeds or variable speed control as maybe required underdifferent circumstances.

In many of the fixed shield embodiments described, the drivers areelectrically powered by mains power introduced into the driver alongcable 34. However, battery power may be used to reduce the hazard of apower cable trailing the driver during surgery. In other embodiments,particularly the retractable shield embodiments, pneumatic or hydraulicpower is used.

Further, whilst generally pencil shaped housing configurations have beendescribed, other embodiments include alternate configurations such aspistol-styled housings.

Although the invention has been described with reference to specificexamples, it will be appreciated by those skilled in the art, that theinvention may be embodied in many other forms.

What is claimed is:
 1. A compact single unit driver with integral shielddevice for use on a body part in surgery, the driver including:a housingadapted for single handed gripping operation; engagement meansassociated with said housing for releasably engaging an end of alongitudinally extending driven member; drive motor for rotatablydriving the engagement means; longitudinally extending non-rotatingshield connected with an end of the housing, the shield extendingco-axially with and circumscribing the driven member, the distal end ofthe shield terminating in an end portion adapted to be placed against asurface of the body part toward which the driven member is to be driven;and means to permit relative movement in an axial direction between theengagement means and the end portion of the shield for advancement ofthe driven member toward the body part and retraction therefrom, whereinin use the engagement means and a portion of the driven member above thesurface of the body part are always fully shrouded by the housing andthe shield and wherein the driven member in an inoperative modeprotrudes from the shield to facilitate accurate positioning prior touse and the driven member is retractable, relative to the end portion,prior to use to allow the end portion to be placed against a surface ofthe body part prior to use.
 2. A driver according to claim 1 wherein theshield means is sized to also act as a guide for the driven member.
 3. Adriver according to claim 1 wherein the shield includes guide meansadjacent the end portion of the shield.
 4. A driver according to claim 1wherein the driven member is selected from the group consisting of adrill bit, a screw, and a Kirschner wire.
 5. A driver according to claim1 wherein the engagement means is fixed relative to the housing and theshield is retractable into the housing as the driven member is advancedthrough the surface into the body part.
 6. A driver according to claim 5wherein the shield is retractable against a biasing means that urges theshield toward the surface of the body part.
 7. A driver according toclaim 6 wherein the shield means is retractable against a biasing meansthat urges the shield means toward the surface.
 8. A driver according toclaim 7 wherein the shield comprises at least two cylindrical concentrictelescoping portions that decrease in diameter towards the end portion.9. A driver according to claim 5 wherein the retractable shield ismarked externally with gradations indicative of the penetration depth ofthe driven member beyond the end portion.
 10. A driver according toclaim 5 wherein the depth indication is provided on the housing by anindication means responsive to the retraction of the shield.
 11. Adriver according to any one of claims 6 to 9 wherein the depthindication is provided directly or indirectly on the housing by asuitable indication means responsive to the retraction of the shieldmeans.
 12. A driver according to any one of claims 6 to 11 wherein thedrive means comprises a flexible drive powered by a motor providedexternal to the housing.
 13. A driver according to any one of claims 1to 5 wherein the shield means is rigidly connected to or forms part ofthe housing and the engagement means are adapted to move internallyrelative to the housing between a retracted position in which the drivenmember is substantially located within the shield means and an extendedposition in which a part of the driven member protrudes from the shieldmeans as it is driven into the surface.
 14. A driver according to claim13 wherein the driver is adapted to receive a plurality ofinterchangeable shield portions for use with varying sized drivenmembers.
 15. A driver according to claim 13 or claim 14 wherein thedrive means includes a first motor which is internal or external to thedriver.
 16. A driver according to claim 15 wherein the driver includes atelescopic coupling operatively connecting an internal first motor tothe engagement means, the motor being fixed relative to the shield meansand the engagement means being configured to travel along the rotationalaxis of the driven member to move the driven member between theretracted and extended positions.
 17. A driver according to claim 15wherein the engagement means and an internal first motor travel alongthe rotational axis together.
 18. A driver according to claim 15 whereinthe first motor is external to the drill and includes a flexiblecoupling operatively connecting the first motor to the engagement means.19. A driver according to claim 15 wherein the first motor is adapted toboth rotationally drive the engagement means and to extend and retractthe engagement means and hence the driven member.
 20. A driver accordingto claim 15 wherein the first motor rotationally drives the engagementmeans only and a second motor is adapted to extend and retract theengagement means and hence the driven member.
 21. A driver according toanyone of claims 13 to 20 including gear means operatively connected toany or all of the motors or engagement means for extension andretraction of the engagement means.
 22. A driver according to claim 21wherein the gear means includes selectively operable advancement andretraction gears for extending and retracting the engagement means. 23.A driver according to claim 21 utilizing only a single gear incombination with a bidirectional motor.
 24. A driver according to anyone of claims 13 to 18 wherein the engagement means are adapted to beadvanced and retracted manually.
 25. A driver according to any one ofclaims 13 to 24 including means to provide an external readingindicative of depth of penetration of the driven member.
 26. A driveraccording to any one of claims 21 to 25 including a variable speed gearbox between the first motor and the engagement means.
 27. A driveraccording to any one of claims 15 to 25 wherein the first motor is avariable speed motor.
 28. A driver according to any one of the precedingclaims wherein the engagement means is in the form of a chuck deviceadapted to receive a variety of sizes of driven members.
 29. A driveraccording to any one of claims 1 to 27 wherein the engagement means ispreferably a snap-lock type or friction style connector adapted toreceive driven members having commonly sized and shaped proximal endportions.
 30. A driver according to any one of the preceding claimswherein the end portion of the shield includes a spike means to engagethe surface into which the driven member is to be driven so as toprevent the driver from wandering.
 31. A driver according to any one ofthe preceding claims in combination with a plurality of driven membersof various type and size each having at their proximal ends a commonsized and shaped head portion for engagement with a correspondinglysized drive coupling forming the engagement means of said driver.
 32. Adriver according to any one of claims 1 to 30 in combination with one ormore adaptors for driven members, each adaptor comprising at one end astandard sized and shaped head portion for engagement with acorrespondingly sized drive coupling forming said engagement means ofsaid driver, said adaptor being configured at said other end remote saidfirst end for torque transmitting attachment to a driven member of agiven size.